<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>天气案例_深度监视</title>
    <script type="text/javascript" src="../js/vue.js"></script>
</head>

<body>

    <div id="root">
        <h2>天气很{{info}}</h2>
        <button @click="changeWeather">切换天气</button>

    </div>

    <script type="text/javascript">
        const vm = new Vue({
            el: '#root',
            data: {
                isHot: true,

            },
            computed: {
                info() {
                    return this.isHot ? '炎热' : '寒冷'
                }
            },
            methods: {
                changeWeather() {
                    this.isHot = !this.isHot
                }
            },
            // 监视的第一种写法
            watch: {
                // 正常写法
                // isHot: {
                //     handler(newValue, oldValue) {
                //         console.log('isHot被修改', newValue, oldValue)
                //     }
                // },

                //简写
                isHot(newValue, oldValue) {
                    console.log('isHot被修改', newValue, oldValue)
                }
            }
        })

        // 第二种方式简写
        vm.$watch('isHot', function (newValue, oldValue) {
            console.log('isHot被修改', newValue, oldValue)
        })


    </script>

</body>

</html>